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gastric pancreatic metaplasia

Sunday 4 March 2012

Pancreatic (Acinar) Metaplasia

Pancreatic metaplasia is present in 12% ofpatients with autoimmune gastritis, usually developing in the cardia and often coexisting with other types of metaplasia.

Pancreatic acinar cells can also develop in the gastric antral mucosa in areas of intestinal metaplasia or atrophy.

The metaplastic foci contain single or multiple pancreatic nests and lobules measuring upto 1.7 mm in diameter.

The metaplastic tissue imperceptibly merges with the gastric glands.

Less commonly, acinar cells lie scattered individually or in small cellular foci among the gastric glands.

Larger lobules contain tubules or small cystic spaces reminiscent of dilated ductules.

The layers of smooth muscle cells that circumferentially surround the ducts in heterotopic pancreas are absent.

The acinar cells have a truncated pyramidal shape with a rim of deeply basophilic basal cytoplasm and numerous small, acidophilic, weakly PAS-positive, refractile granules in the mid- and apical cytoplasm.

These granules contain trypsin, amylase, and lipase.

The nuclei appear round, relatively small, and centrally or basallylocated, with a prominent nucleolus.

Endocrine cells positive for somatostatin, gastrin, or serotonin intermingle with the acinar cells.

Amphicrine cells containing both zymogen and neurosecretory granules are also present.

The metaplastic cells probably result from aberrant stem cell differentiation.

PDX-1, a homeodomain transcription factor, plays a key role in both endocrine and exocrine pancreatic differentiation and differentiation of endocrine cells in the gastric antrum.

Therefore, it is of interest that both the pancreatic metaplasia and endocrine cell hyperplasia associated with atrophic corpus gastritis express PDX-1.